1. Field of the Description
The present invention relates, in general, to improved techniques for controlling humanoid robots and other bipedal robots, and, more particularly, to control methods and controllers for bipedal robots that provide enhanced balancing especially when the robots are placed in dynamic and, oftentimes, unstable environments.
2. Relevant Background
Robots or robotic devices, including bipedal robots (which may be humanoid robots) are widely used in manufacturing, assembly, packing and packaging, earth and space exploration, surgery, laboratory research, and entertainment. Some robots may include a series of rigid links or bodies linked together by joints, and some or all of the links may be moved or pivoted about the joints by actuators. Actuators are like the muscles of a robot as they respond to control signals, such as from a control system or controller, to convert energy into movement. The majority of robots use electric motors (DC or AC motors) as actuators to spin a wheel or gear while some actuators are provided in the form of linear actuators or other types of actuators. A hand (or foot) of a robot may be referred to as an end effector while the arm (or leg) is referred to as a manipulator, and these systems or devices of the robot may be made up of a number of rigid links or members interconnected by joints with movement at the joints controlled by actuators.
An ongoing challenge for those in the field of robotics is how to best or better control a bipedal robot. Particularly, dynamic balancing of bipedal robots is one of the most fundamental yet challenging problems in robotics research. Research has generated a large body of literature and control theories in the areas of controlling bipedal robots including postural balancing, push recovery, and walking. Several bipedal robots have been built that exploit the passive dynamic stability in the sagittal plane. However, the majority of bipedal robotics research has focused on balancing and motion generation in the sagittal plane. Further, the controllers for these bipedal robots was written or generated with the underlying assumption that the environment properties are known, which allows the environment and the bipedal robot to be modeled and then control theory to be applied to provide a useful controller.
There remains a need for a controller for bipedal robots that is useful for providing robust lateral stabilization in many types of changing or varying environments and not just in known stable environments. In other words, a universal balancing controller is desired for using in controlling bipedal robots in dynamic environments that may also be unstable. For example, humans have the ability to successfully balance in both static and dynamic environments, and it would be useful to provide a robot controller (or control methods) that enables a bipedal robot to stabilize dynamic, unstable environments such as a bipedal robot positioned on a seesaw or a bongo board.